1. Field of the Invention
The present invention relates to a presentation supporting system which takes a visual image of a material placed on a table with a video camera and outputs a reproduction image representing the material to an external display unit, and also to a control device used in the presentation supporting system.
2. Description of the Related Art
Over-head projectors (OHP) are most popular visual presenters used in a variety of fields. With significant improvement of CCD (charge coupled device) cameras, novel presentation supporting systems using a CCD camera have been developed and proposed. In such a presentation supporting system, a visual image of a material, a sample, or another subject matter placed on a table is taken with a CCD camera disposed above the table, and is output as video signals to an external television set or video tape recorder. Stationary presentation supporting systems generally include a video camera such as a 3-plate CCD camera which requires a relatively large space.
In the presentation supporting system with a large-sized CCD camera for expanding a shooting range, the CCD camera with a certain lens system should be held with an arm member a predetermined distance apart from the material on the table to ensure a required shooting distance. This makes the whole presentation supporting system undesirably large and bulky. Such large-sized presentation supporting systems do not cause significant problems in the process of presentation, but cause bulky packaging and difficulty in shipment and require a large space for storage.
The above problem may be solved by an improved structure where the arm member for holding the CCD camera is folded from its base as a support arm of a condenser of the OHP. This improved system still has a problem that a long arm member for holding the CCD camera at a certain position sufficiently apart from the table is partly located out of the table under the folded condition. This requires a packaging box to have a relatively complicated shape.
A novel presentation supporting system which can be compactly stored and packed in a simple shape of a packaging box has accordingly been required.
With rapid development of image processing technology, advanced functions have been added to the presentation supporting system.
In a typical presentation supporting system with advanced functions, the operator can arbitrarily set presentation conditions including selection of lighting, selection of data input, the iris conditions, selection of either B&W display or color display, and the color balance. The presentation conditions further include the amplification or sound volume when a microphone can be connected to the presentation supporting system. The operator can also select an external display system for showing a reproduction image out of plural options or an input system of video signals out of plural options. In the multi-functional presentation supporting system, effective presentation including clear reproduction is attained through adequate adjustment of these presentation conditions.
With significant increase in the presentation conditions, a relatively long time is required for adjustment of these conditions. For example, when the material placed on the table is a type-written sheet or sample, an auxiliary lighting unit disposed above the table is generally used as a reflected light source. When the material is a X-ray film or slide, on the other hand, a base light unit built in the table is generally used as a transmitted light source. The iris control and the color balance should also be varied according to the type of the material. These conditions are generally adjusted by operating a variety of switches mounted on the presentation supporting system. These is, however, a problem that the presentation conditions once set by an operator, for example, for X-ray films are returned to the initial settings every time when the power is turned off, or are changed to other conditions when another operator uses the system to show another type of material.
In actual presentation, a plurality of materials should be shown within a short time period. The materials used in presentation are prepared to meet an identical set of presentation conditions since manual adjustment of the presentation conditions requires a relatively long time. In other cases, a plurality of presentation supporting systems are used to show different types of materials.